Abstract

The way in which quality is modelled within an organisation has typically followed either a fixed-model or a tailorable approach. Fixed-model techniques suffer the disadvantage of inflexibility to local environments, since, the parameters of these models cannot be changed by users or designers to reflect their own views. The tailorable approaches tend to preclude cross-project comparisons. In addition, both techniques lack comprehensive guidelines for building quality into a software product, and lack the ability to resolve conflicts where individuals disagree about the model parameters. In this work, the construction of a new approach is described which overcomes these deficiencies. Since metrics and metric measurement is an important component of quality models, common metrics and measurement techniques are identified, before the construction and evaluation of the new quality modelling approach is presented.
A common metric is software size, measurement of which can be performed by use of the Function Point Analysis (FPA) technique. The weighting and adjustment factors of the traditional FPA approach are simplified here, to produce a new estimation technique which can be used at early stages in the development lifecycle. The new model is validated against two project datasets, and the results show a good degree of accuracy when estimating the FPA count, although a lower performance is achieved when estimating actual effort.
The major component of this thesis is the construction of the new quality modelling approach, that enables local requirements tailoring whilst providing the ability to perform cross-project comparisons. Unlike existing techniques, comprehensive conflict resolution mechanisms are incorporated, and it is shown that the approach can be used to measure different software entities, allowing direct comparisons between measurements and thus producing more consistent results. The implementation consists of the construction of a software tool supporting the new methodology, and use of both this tool and the technique on real projects at a large financial organisation. The validation of the approach is performed against a list of requirements for a good quality model, and from feedback both from use on the projects and from a questionnaire survey.